U.S. patent number 5,848,587 [Application Number 08/826,554] was granted by the patent office on 1998-12-15 for aerosol medication delivery system.
This patent grant is currently assigned to Medi-Nuclear Corporation, Inc.. Invention is credited to Russell W. King.
United States Patent |
5,848,587 |
King |
December 15, 1998 |
Aerosol medication delivery system
Abstract
An aerosol medication delivery apparatus which includes a novel
particle generator for generating very small particles of
medicament, a valving mechanism and an expansion chamber which
permits medication to be delivered to the patient through a
conventional inhalation mouthpiece or face mask. The apparatus also
includes a filter unit for filtering the patient's exhaled breath
and a unique baffling arrangement which functions to decrease
average aerosol particle size for better targeting of the desired
lung area. In one form of the invention, the particle or aerosol
generator operates on a direct pressure technique wherein an
elastomeric delivery tube is intermittently compressed and released
to generate the very small particles of medicament.
Inventors: |
King; Russell W. (Baldwin Park,
CA) |
Assignee: |
Medi-Nuclear Corporation, Inc.
(Baldwin Park, CA)
|
Family
ID: |
46252589 |
Appl.
No.: |
08/826,554 |
Filed: |
April 4, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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531697 |
Sep 21, 1995 |
5617844 |
|
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Current U.S.
Class: |
128/200.18;
128/200.14; 128/200.23 |
Current CPC
Class: |
A61M
11/002 (20140204); A61M 15/0098 (20140204); A61M
11/001 (20140204); A61M 16/208 (20130101); A61M
15/0015 (20140204); A61M 16/1065 (20140204); A61M
15/009 (20130101); A61M 15/0086 (20130101); A61M
15/0016 (20140204); A61M 15/0018 (20140204); A61M
15/008 (20140204); A61M 2016/0024 (20130101); A61M
16/1055 (20130101); A61M 16/0093 (20140204); A61M
16/105 (20130101) |
Current International
Class: |
A61M
15/00 (20060101); A61M 16/20 (20060101); A61M
16/10 (20060101); A61M 16/00 (20060101); A61M
11/00 (20060101); A61M 011/00 () |
Field of
Search: |
;128/200.14,200.18,200.23 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lewis; Aaron J.
Attorney, Agent or Firm: Brunton; James E.
Parent Case Text
This is a Continuation-In-Part of application Ser. No. 08/531,697
filed Sep. 21, 1995, now U.S. Pat. No. 5,617,844.
Claims
I claim:
1. A fluid delivery apparatus comprising:
(a) a housing having interconnecting first and second chambers;
(b) flow control means carried by said housing for controlling
passage of fluid between said first and second chambers;
(c) particle generator means connected to said housing for
introducing a fluid into said first chamber of said housing, said
particle generator means comprising:
(i) container having a fluid reservoir;
(ii) an elongated tube connected to said container, said tube
having a side wall defining a fluid passageway and having first end
connected to said container, said tube being constructed of a
resiliently compressible, elastomeric material and having a second
end extending into said first chamber;
(iii) a closure means connected to said second end of said tube for
partially closing said second end, said closure means comprising a
wafer having a multiplicity of small apertures therethrough;
(iv) flow actuator means for exerting intermittent forces of said
side wall of said tube; and
(v) valve means for controlling fluid flow between said reservoir
of said container and said fluid passageway of said tube, said
means comprising a normally open valve movable from first open
position to a second closed position as a result of forces being
exerted on said side wall of said tube by said flow actuator
means.
2. An apparatus as defined in claim 1, in which said housing
further includes a wall having an opening therein, said wall being
disposed intermediate said first and second chambers and in which
said flow control means comprises a valve member pivotally movable
relative to said opening in said wall.
3. An apparatus as defined in claim 1 in which said housing
includes an outlet port in communication with atmosphere, and in
which said apparatus further includes filtering means connected to
said housing for filtering particulates from the particulate-laden
mist flowing through said outlet port.
4. An apparatus as defined in claim 1 in which said flow actuator
means comprises tube compression means for alternatively
compressing and releasing said side wall of said tube.
5. An apparatus as defined in claim 4 in which said tube
compression means comprises a compression assembly including:
(a) a body having a chamber;
(b) a shaft extending outwardly from said body; and
(c) a tube engaging protuberance connected to said shaft for
intermittently, pressurally engaging said tube.
6. An aerosol inhalation apparatus for delivering a medicament
containing mist to a patient comprising:
(a) a housing having interconnecting first and second chambers and
including a wall having an opening therein, said wall being
disposed between said first and second chambers;
(b) flow control means carried by said housing for controlling
passage of fluid between said first and second chambers, said flow
control means comprising a valve means for opening and closing said
opening in said wall;
(c) particle generator means connected to said housing for
introducing a fluid into said first chamber of said housing, said
particle generator means comprising:
(i) a container having a fluid reservoir;
(ii) an elongated tube connected to said container, said tube
having a side wall defining a fluid passageway and having first end
connected to said container, said tube being constructed of a
resiliently compressible, elastomeric material and having a second
end extending into said first chamber;
(iii) a closure means connected to said second end of said tube for
partially closing said second end, said closure means comprising a
wafer having a multiplicity of small apertures therethrough;
(iv) valve means for controlling fluid flow between said reservoir
of said container and said fluid passageway of said tube, said
means comprising a normally open valve movable from first open
position to a second closed position; and
(v) flow actuator means for exerting intermittent forces of said
side wall of said tube, said flow actuator means comprising tube
compression means for alternately compressing and releasing said
side wall of said tube.
7. An apparatus as defined in claim 6 in which said tube
compression means comprises a compression assembly including:
(a) a body having a chamber;
(b) a shaft extending outwardly from said body; and
(c) a tube engaging protuberance connected to said shaft for
intermittently pressurally engaging said tube.
8. An apparatus as defined in claim 7 in which said compression
assembly further includes a piston reciprocally movable within said
chamber, said shaft being connected to said piston.
9. An apparatus as defined in claim 7 in which said compression
assembly further includes a motor means carried within said chamber
for rotating said shaft to move said tube engaging protuberance
intermittently into engagement with said tube.
10. An aerosol inhalation apparatus for delivering a medicament
containing mist to a patient comprising:
(a) a housing having interconnecting first and second chambers and
including a wall having an opening therein, said wall being
disposed between said first and second chambers;
(b) flow control means carried by said housing for controlling
passage of fluid between said first and second chambers, said flow
control means comprising valve means for opening and closing said
opening in said wall, said valve means comprising a valve member
pivotally connected to said housing proximate said opening in said
wall;
(c) particle generator means connected to said housing for
introducing a fluid into said first chamber of said housing, said
particle generator means comprising:
(i) container having a fluid reservoir;
(ii) an elongated tube connected to said container, said tube
having a side wall defining a fluid passageway and having first end
connected to said container, said tube being constructed of a
resiliently compressible, elastomeric material and having a second
end extending into said first chamber;
(iii) a closure means connected to said second end of said tube for
partially closing said second end, said closure means comprising a
wafer having a multiplicity of small apertures therethrough;
(iv) valve means for controlling fluid flow between said reservoir
of said container and said fluid passageway of said tube, said
means comprising a normally open valve movable from first open
position to a second closed position; and
(v) flow actuator means for exerting in termittent forces of said
side wall of said tube, said flow actuator means comprising tube
compression means for alternately compressing and releasing said
side wall of said tube, said tube compression means comprising a
compression assembly including:
a. a body having a chamber;
b. a shaft extending outwardly from said body; and
c. a tube engaging protuberance connected to said shaft for
intermittently, pressurally engaging said tube.
11. An apparatus as defined in claim 10 in which said compression
assembly further includes a piston reciprocally movable within said
chamber, said shaft being connected to said piston.
12. An apparatus as defined in claim 11 in which said compression
assembly further includes a motor means carried within said chamber
for rotating said shaft to move said tube engaging protuberance
intermittently into engagement with said tube.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to aerosol medication delivery
systems. More particularly, the invention concerns an improved
aerosol inhalation apparatus that is very useful for dispensing
pharmaceuticals in the treatment of respiratory or pulmonary
diseases and for systemic delivery of drugs via aerosolization.
2. Discussion of the Prior Art
Therapeutic aerosols are commonly administered to patients
suffering from numerous types of pulmonary diseases. Specific
medications, include beta.sub.2 agonists, anticholinergies,
cromolyn sodium, and steroids. More recently the aerosol method of
delivery has been used to administer Pentamidine to patients
afflicted with AIDS, and is presently under consideration as a
delivery means for insulin in the treatment for diabetes.
Experience has shown that the use of aerosols to treat lung disease
is highly advantageous in that it produces optimal therapy with
minimum side effects. Both physical and clinical factors affect
aerosol deposition in the lungs. Physical factors include inertial
impaction, sedimentation, and diffusion. Clinical factors include
particle size, ventilatory pattern and lung function. Aerosols
larger than 5 micron aerodynamic diameter (AD) poorly penetrate the
upper respiratory tract. Those in the 0.2 to 2 micron range tend to
have their maximum disposition in the lung parenchyma.
In general the devices used for producing medical aerosols fall
into three categories; the small volume nebulizer (SVN), the
metered does inhaler (MDI), and the powder dose inhaler (PDI).
Although the small volume nebulizer (SVN) has traditionally been
the apparatus of choice for delivery of therapeutic aerosols, many
institutions are now switching to the MDI. The small volume
nebulizer (SVN) apparatus typically consists of disposable or
reusable nebulizer, a mouthpiece or face mask, and a pressurized
gas source usually oxygen or air. The metered dose inhaler (MDI),
on the other hand, typically contains the active drug, a metering
valve, and chlorofluorocarbon (CFC) propellants. The drug
containing canister of the device is generally fitted to a
mouthpiece actuator, and activation by compression of the canister
into the mouthpiece results in the release of a unit dose of
medication.
There is extensive literature indicating the successes of aerosol
therapies, as well as the difficulties of using the aerosols
properly. See, for example, Respiratory Infection: Diagnosis and
Management. J. E. Pennington ed. Raven Press, N.Y. chest 1981,
80:911-915: Arch, Int. Med. 1973, 131:88-91. Notwithstanding the
very considerable development of aerosols and methods of using the
same, there is still room for improvement in the administration of
pharmaceutical aerosols.
A major problem of aerosol therapy is to deposit the aerosol on the
walls of small bronchi and bronchioles, where the action of the
medication is most often required. Less than 10% of the medication
delivered by standard multidose inhalers reaches the typical
patient's lungs. Most of the 90% of the medication which does not
penetrate the target area is deposited in the mouth, throat, and
trachea, and is eventually injested. A small fraction of the
aerosol is exhaled.
For effective utilization, the aerosol should consist of small
particles, less than 5 microns AD, since larger particles cannot
negotiate the sharp turns to the lung and are deposited in the
orophapyny due to inertial effects. In order to minimize mouth
deposition further it has been shown that the volumetric flow rate
of the inhaled aerosol should be below 30 liters per minute. Meter
dose inhalers deliver aerosol at a high initial velocity directly
into the patient's mouth. This high initial velocity of the aerosol
is a major factor in the ineffectiveness of many inhaler
systems.
Another serious problem inherent in MDI aerosol medication is
patient timing coordination. If patient inhalation does not occur
on a timely basis with MDI canister actuation, a large percentage
of the medication is lost.
Several pharmaceutical manufacturers have included, or sold
separately with their MDI aerosol products, what are referred to
variously as "spacers", "oral adaptors", "space-inhalers", and
"spray inhalers" to be used in conjunction with their products.
These offer only a partial solution to the problems which typically
occur in MDI aerosol delivery.
The apparatus of the present invention provides a very substantial
improvement over all prior art MDI-type devices in that it
addresses: (1) volumetric flow rate of medication, (2) elimination
of patient coordination problems, (3) particle size, and (4)
environmental protection considerations.
A somewhat similar aerosol medication delivery system is disclosed
in co-pending application Ser. No. 08/531,697 filed by the present
inventor. Accordingly, this application, Ser. No. 08/531,697, is
hereby incorporated herein by reference as though fully set forth
herein. Reference to this earlier-filed application will show that
the device of the present invention embodies a drug nebulizing
means of a generally different construction and mode of operation
than that disclosed in Ser. No. 08/531,697.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an inhalation
apparatus, which, when used with an MDI-type inhaler, will result
in a substantial increase in the delivery to the patient of
particles in the respirable size range.
Another object of the invention is to provide an apparatus of the
aforementioned character which essentially eliminates patient
timing coordination problems when administering a unit does of
medication.
Another object of the invention is to provide an apparatus which
limits volumetric flow rate of the inhaled aerosol to that of
normal patient breathing, i.e. below 30 liters per minute.
Another object of the invention is to provide a novel apparatus
wherein release of medication from the MDI canister is triggered
automatically by patient exhalation rather than by manual
actuation, thereby providing for timely accessibility during the
next inhalation.
Yet another object of the invention is to provide an apparatus of
the character described wherein the number of desired patient
inhalations can be preselected, and wherein medication availability
will automatically terminate upon reaching that number.
Another object of the invention is to provide an apparatus of the
character described in the preceding paragraphs which embodies a
novel aerosol particle generator which operates on a direct
pressure technique wherein an elastomeric delivery tube is
intermittently compressed and released to generate very small
particles of medicament.
Still another object of the invention is to provide an apparatus as
described in the preceding paragraphs wherein air exhaled from the
patient is safely filtered before it is released to room
atmosphere.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a generally perspective, exploded view of one form of the
aerosol medication delivery system of the invention.
FIG. 2 is a side-elevational, cross-sectional view of the assembled
apparatus shown in FIG. 1.
FIG. 3 is an enlarged, generally perspective, further exploded view
of the form of apparatus shown in FIGS. 1 and 2.
FIG. 4 is a fragmentary, cross-sectional view of the right-hand
portion of the apparatus shown in FIG. 2.
FIG. 5 is a side-elevational view of the mist generator portion of
the apparatus partly in cross section to show internal
construction.
FIG. 6 is an enlarged, cross-sectional view of the area designated
as 6 in FIG. 5.
FIG. 7 is a cross-sectional view taken along lines 7--7 of FIG.
5.
FIG. 8 is a greatly enlarged cross-sectional view of the lower
portion of the mist generator portion of the apparatus illustrating
the construction of the check valve assembly thereof and further
showing the mechanism for activating spray generation.
FIG. 9 is a cross-sectional view similar to FIG. 8, but showing the
components of the device moved into a valve-closed, mist-activating
configuration.
FIG. 10 is a fragmentary, cross-sectional view of an alternate form
of flow activator means of the invention.
FIG. 11 is a view taken along lines 11--11 of FIG. 10.
DESCRIPTION OF THE INVENTION
Referring to the drawings and particularly to FIGS. 1, 2, and 3,
the aerosol inhalation apparatus of one form of the present
invention can be seen to comprise a sectionalized main housing 12
to which is attached filtering means, here provided as a bacteria
filter assembly 14 and a drug nebulizing means, shown here as a
novel aerosol particle generator 16 for generating aerosol
particles by a direct pressure technique. As best seen in FIGS. 1
and 2, generator 16 is removably mounted within an easily
accessible chamber 18 which forms a part of housing 12.
Provided proximate the first end 12a of housing 12 is inhalation
means comprising a standard size breathing port 20 which is coupled
with the patient via a flexible conduit 22 and an appropriate
mouthpiece, or face mask (not shown). In a manner presently to be
described, the various components and interconnecting fluid flow
passageways of the device are uniquely constructed and arranged to
maximize the delivery of properly sized aerosolized medication to
the patient on a timely basis.
Turning particularly to FIGS. 2 and 5, it can be seen that the
nebulizing means, or generator 16 of the apparatus is mounted
within chamber 18 in a manner such that the outlet tube 24 of the
device extends downwardly into an expansion chamber 26 formed in
housing 12. Outlet tube 24, which is constructed from a resiliently
compressible, elastomeric material such as polyethylene, is
connected proximate its first end 24a with a container 30 having a
drug containing reservoir 32. Provided proximate and partially
closing the second end 24b of outlet tube 24 is a closure means
shown here as a perforated wafer 34 (FIG. 7).
Disposed between wafer 34 and reservoir 32 is a valve means, which
is here provided in the form of a normally open check valve
assembly 36 which functions to control the flow of the fluid
contained within reservoir 32 outwardly of the reservoir and into
the internal passageway 24c of tube 24.
By way of background, the controlled generation of aerosol
particles by nebulizers of the character described in Ser. No.
08/531,697 is, of course, well known. However, aerosol particles
can also be generated when sufficient pressure is applied to a
liquid to force it through small apertures at a velocity sufficient
to form very small fluid jets. These small fluid jets will
effectively break up under the influence of surface tension effects
to form an aerosol comprising a multiplicity of very small
particles. This direct pressure technique has been used for more
than twenty years in creating fog (aerosol droplets in the 10-20
micron range) for cooling and for various agricultural purposes.
More recently, the technique has been used for producing medical
aerosols. (See, for example, "A New Unit Dose, Breath Actuated
Aerosol Drug Delivery System", Peter Lloyd et al, Respiratory Drug
Delivery V, Apr. 28, 1996-May 2, 1996 Phoenix, Ariz.)
In the particle generator of the apparatus of the present
invention, high pressure surges are applied to the liquid
medicament contained within the delivery tube of the device in a
manner to produce aerosol particles from aliquots of liquid
medicament contained within an internal passageway 24c of the tube
24 thereby producing a continuous supply of aerosol medication for
patient use. This novel generator, when integrated into the
delivery system of the apparatus will, in a manner presently to be
described, efficiently provide continuous nebulization without, in
any way, sacrificing the compactness, simplicity and portability of
the apparatus.
As shown in FIG. 7, perforated wafer 34 is provided with a
multiplicity of small apertures 34a which are preferably on the
order of 2 microns in size. With this construction, when the liquid
medicament contained within passageway 26c of the tube is forced
through wafer 34 at a very high velocity, a fine particulate laden
spray will be produced. Wafer 34 can be constructed of a porous
ceramic, a sinteed metal, or a thin metal or ceramic disc which has
been precisely laser drilled. The spray produced by this pressure
technique comprises a multiplicity of medicament particles of
various sizes which are expelled under pressure into expansion
chamber 26 that is disposed immediately below chamber 18 and into
which end 24a of tube 24 extends.
To exert pressure on the aliquot of fluid contained within the
delivery tube so as to cause the medicament particles to be
controllably expelled into expansion chamber 26, a novel flow
actuator means is provided. In one embodiment of the invention, the
actuator means comprises an actuator assembly 40 which includes
compression means for intermittently compressing and releasing the
side wall 24e of tube 24 with sufficient force to cause the
production of the particulate laden spray in the manner shown in
FIG. 4. This compression of the side wall of the tube by the
compression means changes the internal, cross-sectional
configuration of the tube from being generally circular to being
generally elliptical, thereby sharply reducing the volume of the
internal passageway of the tube.
As previously mentioned, valve means are provided to control the
flow of fluid from reservoir 32 into tube 24. These valve means,
which comprise valve assembly 36, includes a generally spherical
valve member 42 which is disposed within an enlarged neck portion
24d of tube 24. Member 42 is movable from the first valve open
position shown in FIGS. 5, 6 and 8, where it is supported within
neck portion 24d by circumferentially spaced legs 43, to a valve
closed position shown in FIG. 9 where it seats against an internal
valve seat 44 provided proximate neck 30a of container 30. In a
manner presently to be described, valve member 42 moves into the
second valve closed position in response to fluid pressure
generated within the internal passageway 24c of the tube 24 by the
flow actuator means of the invention. When valve member 42 is in
the valve open position shown in FIG. 8, the liquid medicament
contained within reservoir 32 is free to flow by force of gravity
into and substantially fill the internal passageway 24c of tube 24.
To permit proper venting during the tube-fill step, vent means "V"
in the form of a small screw cap (FIG. 5) is provided.
In one form of the invention, the important flow actuator means
comprises a tube compression means or compression assembly 40 which
is connected to housing 12 in the manner shown in FIG. 2. Assembly
40 includes a body 50 having a chamber 52 within which a piston 54
is reciprocally carried. Connected to piston 54 and extended
outwardly from body 50 is an actuator shaft 56 which has a tube
compressing protuberance 58 formed proximate the end thereof. When
piston 54 and shaft 56 are moved outwardly from the first position
shown in FIG. 8 to the tube compression position shown in FIG. 9,
substantial pressure will be exerted on the fluid within tube 24
causing valve member 42 to rapidly move into the valve closed
position shown in FIG. 9. This sharp exertion of pressure on the
fluid trapped within the now closed passageway 24c of tube 24 will
force the fluid through the apertures 34a formed in wafer 34 with
sufficient force to form a multiplicity of very fine fluid jets 57
(FIG. 4). These jets, under the influence of surface tension
effects will break up into aerosol droplets of various sizes as,
for example, droplets in the 10 to 20 micron size range. Repeated
rapid intermittent compression and relaxation of tube wall 24e by
the flow actuator means will produce a consistent, uniform flow of
very small aerosol particles into expansion chamber 26 in the
manner shown in FIG. 4.
Piston 54 can be reciprocated within chamber 52 of body 50 by
hydraulic or pneumatic means in a manner well known to those
skilled in the art. When piston 54 is driven hydraulically or
pneumatically, the driving fluid can be introduced into chamber 52
via conduit 58 (FIG. 4). Piston 54 can also be reciprocated within
chamber 52 electrically using a solenoid arrangement of a character
well known to those skilled in the art.
Additional forces can be exerted on tube wall 24e by other
mechanical means such as those shown in FIGS. 10 and 11 of the
drawings. In the alternate form of flow actuator of the invention
shown in these figures, the tube compression means or compressor
assembly, comprises a body 57 which houses motor means provided as
an electric motor 58 which controllably rotates a shaft 59.
Provided at the end of shaft 59 is wheel 59a upon which a tube
engaging protuberance 59b is eccentrically mounted. Motor 58 is
energized via an electrical conduit 58a and, when energized, causes
shaft 59 to rotate in a manner to bring protuberance 59b into
pressural contact with tube 24 twice for each resolution of the
shaft. As the protuberance compresses, the tube fluid contained
within passageway 24c will be forced outwardly through wafer 34 to
form the particulate laden spray.
Without regard to the particular mechanism used to intermittently
compress tube wall 24e when pressure on the wall is intermittently
released, the valve member will move into the open position shown
in FIG. 8 thereby permitting another aliquot of medicament to flow
from reservoir 32 into tube 24. In the manner previously described,
this novel and efficient pressure technique will simply and
reliably provide a continuous controlled flow of very small
particles of medicament into expansion chamber 26.
Obviously, the amount of drug medication being converted to aerosol
is determined by the volume of liquid displaced per actuation of
the actuator means and the number of actuations per minute. The
rate of compression and relaxation of tube wall 24e can readily be
controlled to provide a precise aerosol generation rate. Therefore,
it is readily apparent that novel pressure technique of the
invention as described in the preceding paragraphs can be optimized
for drug delivery to meet a wide variety of clinical demands.
During use of the apparatus in patient treatment, the patient's
exhaled air is received by filter assembly 14 via a first valve
means, shown here as a one-way ball check valve 62 of standard
construction. During patient exhalation, a nominal amount of
resistance to air flow is caused by valve 62 which creates a slight
over pressure in a second forward chamber 20, thereby maintaining
the novel flow control or pivoting valve assembly 64 of the
invention in a closed position. Accordingly, if the particle
generator means is actuated during patient exhalation, the
aerosolized medicament produced thereby is securely contained with
expansion chamber 26 for use during the next patient
inhalation.
Upon patient inhalation, valve assembly 64 opens so that all
medication from chamber 26 is carried through chamber 20 and into
the patient's lungs via conduit 22 and the mouthpiece or face mask.
If the particle generator means is actuated during the time of
patient inhalation, the medication will, of course, enter the air
stream and flow directly to the patient's lungs. Thus, the system
as described uniquely provides for delivery of the desired patient
dose with no concern as to the timing of medication released from
the particle generator device. Also, the flow rate of medication to
the patient is strictly a function of patient breathing only,
thereby optimally allowing the medication to clear the patient's
throat area and flow freely into the patient's lower lung
compartments.
As indicated in FIGS. 8 and 9, the flow control means, or assembly
64, is of substantially identical construction and operation to the
flow control means 40 described in Ser. No. 08/531,697 which is
incorporated herein by reference. Accordingly, this important flow
control means will not be further discussed in detail herein.
Connected to chamber 26 and in communication therewith is settling
means shown here as a settling chamber 66 which is threadably
connected to housing 12 and functions to remove large particles
from the particulate laden mist by means of sedimentation. The
provision of a baffle means, here comprising an upstanding wall 68
(FIGS. 2 and 4) which interferes with the flow of the larger
particles, also contributes to the reduction of the number of large
particles contained within the particulate laden spray which reach
the patient.
As is the case with the form of the invention described in Ser. No.
08/531,697, the apparatus of the present invention will function
equally well with or without filter assembly 14. In those instances
where medicament should not be released to the environment, a
filter means such as filter assembly 14, which is identical to that
described in the application incorporated herein by reference, can
be provided to filter particles from the spray flowing into chamber
20 and outwardly to atmosphere via outlet port 14a as a result of
patient exhalation.
In operating the apparatus of the present form of the invention,
the particle generator 16 is first inserted into chamber 18 in the
inverted position shown in FIG. 2 so that end 24b of tube 24 is
received within expansion chamber 26. With the generator thusly
positioned, the liquid medicament contained within the generator
will flow into tube 24 via normally open valve assembly 36.
Operation of the flow actuator means will then cause a medicament
laden mist to plume outwardly from end 24a of tube 24 and into
expansion chamber 26 in the manner shown in FIG. 4.
Upon patient inhalation, a conventional check valve assembly 67
which is mounted within the base 66a of a housing 66 that is
threadably connected to housing 12 will open permitting air to
enter expansion chamber 26 in the direction of the arrows
identified by the numerals 69 in FIG. 2. This air will mix with the
particulate laden mist and will flow upwardly of the device through
passageway 64a where it will impinge upon diaphragm 64b of valve
assembly 64 causing it to pivot into the open position shown in
FIG. 4. As the mixture of air and particulate laden mist enters
chamber 20, valve 62 will be urged into its closed position and the
particulate laden mist and air mixture will enter flexible conduit
22 and flow toward the patient.
As in the earlier described embodiments, the baffle means or baffle
wall 68 partially blocks entrance to chamber 20 and impedes the
progression of the larger particles contained within the
particulate laden mist as the mist tends to flow toward chamber 20.
Baffle wall 68 is strategically located and designed so that the
larger particles, contained within the particulate laden mist, will
be unable to pass over the barrier and will fall by force of
gravity into chamber 26. This important aspect of the invention
prevents the undesirable flow of larger particles of medicament
toward the patient via chamber 20.
When the patient exhales, check valve 62 will move into the open
position permitting the exhaled breath to enter filter assembly 14
were it is completely filtered prior to entering the atmosphere via
outlet port 14a of the device. With this unique construction, upon
patient exhalation, the flexible diaphragm member 64b of flow
control means or assembly 64 will close, blocking fluid flow
through opening 64a.
Having now described the invention in detail in accordance with the
requirements of the patent statutes, those skilled in this art will
have no difficulty in making changes and modifications in the
individual parts or their relative assembly in order to meet
specific requirements or conditions. Such changes and modifications
may be made without departing from the scope and spirit of the
invention, as set forth in the following claims.
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